Left 4 Dead 2

This is obviously a serious problem for ALOT of people (..um..a few pages if you look up "weapon switch"...)...I thought it was just background programs running...it isn't up til a few days ago, my sytem ran L4D2 just fine, a little lag here and there on remote servers, blah blah blah, nothing out of the ordinary. Suddenly, and without warning, when the special infected appear, i get lag, not connection lag, game lag...ok, this may be to my own benifit, seeing as to how my music is turned all the way off, i get a little heads-up, a half second twitch in the game...no biggie..Then, almost as suddenly, and with less warning, a few day later, when I switch my weapons, my whole game stutters and lags itself to the point where my system almost crashes...EVERYTHING stops, for like two, seconds...in that two seconds, alot happens, I get incapped...my buddies shoot me...I loose total control of my guy...then I get kicked for being a "n00b", or whatever...(btw...I've been playing FPS games since Duke Nukem came out with the first mouse-keyboard setup, there was no such thing as "n00bs" back then...). It's not server lag...i was filming with Bandicam and had a 19 ping (and...i use wi-fi) the whole time I was switching back and forth in my hud, while I was standing next to a crying witch...my ping went up to 21 a couple times...so that wasn't it...Ive gone in and shut down all my bs updaters in the startup menu, unnessisary processes, defragged, and verified game files..from what I read, not even reinstall will fix it...need feedback on this...something that will work...Maybe instead of new skin mods, the Devs should work on current techincal issues, and have the updates actually fix them...

Ok..in case if it matters...my system is an HP 2000 notebook with an AMD E-300 APU with Radeon(tm) Graphics, 1300 MHz, 2 Core(s), 2 Logic Processor(s)...its got 4Gb RAM chip...Total Physical 3.60Gb /2.23Gb Available memory...Total virtual memory is 7.21GB/5.49 Available virtual memory...it's not like this thing can't handle this game...I usually run the definitions fairly low...with the music turned off...and, the whole time I was filming, I wasn't using the mic at all (it's on "push to talk" anyways, so it was off)...I don't run other junk in the background when I play...I like my ping to be very, very, very low (and who doesn't?)...maybe its a Dual-core issue? (btw...it was doing this before I ever tried filming it...)

Try with and without multicore rendering and see if it works better. It could be that your clock speed isn't high enough. Even with that amount of cores, it still can be an issue, because getting a better one fixed mine literally and the game was running very decent with only one.